azureblob

Documentation

Overview

Package azureblob provides a blob implementation that uses Azure Storage’s BlockBlob. Use OpenBucket to construct a *blob.Bucket.

Open URLs

For blob.OpenBucket URLs, azureblob registers for the scheme "azblob"; URLs start with "azblob://", like "azblob://mybucket". blob.OpenBucket will obtain credentials from the environment variables AZURE_STORAGE_ACCOUNT, AZURE_STORAGE_KEY, and AZURE_STORAGE_SAS_TOKEN. AZURE_STORAGE_ACCOUNT is required, along with one of the other two. If you want to obtain this information differently or find details on the format of the URL, see URLOpener.

For more on SAS tokens, see https://docs.microsoft.com/en-us/azure/storage/common/storage-dotnet-shared-access-signature-part-1#what-is-a-shared-access-signature

Escaping

Go CDK supports all UTF-8 strings; to make this work with providers lacking full UTF-8 support, strings must be escaped (during writes) and unescaped (during reads). The following escapes are performed for azureblob:

• Blob keys: ASCII characters 0-31, 92 ("\"), and 127 are escaped to "__0x<hex>__". Additionally, the "/" in "../" and a trailing "/" in a key (e.g., "foo/") are escaped in the same way.
• Metadata keys: Per https://docs.microsoft.com/en-us/azure/storage/blobs/storage-properties-metadata, Azure only allows C# identifiers as metadata keys. Therefore, characters other than "[a-z][A-z][0-9]_" are escaped using "__0x<hex>__". In addition, characters "[0-9]" are escaped when they start the string. URL encoding would not work since "%" is not valid.
• Metadata values: Escaped using URL encoding.

As

azureblob exposes the following types for As:

• Bucket: *azblob.ContainerURL
• Error: azblob.StorageError
• ListObject: azblob.BlobItem for objects, azblob.BlobPrefix for "directories"
• ListOptions.BeforeList: *azblob.ListBlobsSegmentOptions
• Reader: azblob.DownloadResponse
• Attributes: azblob.BlobGetPropertiesResponse
• WriterOptions.BeforeWrite: *azblob.UploadStreamToBlockBlobOptions

Example

package main

import (
	"context"
	"log"

	"github.com/Azure/azure-storage-blob-go/azblob"
	"gocloud.dev/blob/azureblob"
)

func main() {
	const (
		// Your Azure Storage Acount and Access Key.
		accountName = azureblob.AccountName("my-account")
		accountKey  = azureblob.AccountKey("my-account-key")
		// The storage container to access.
		containerName = "mycontainer"
	)

	// Create a credentials object.
	credential, err := azureblob.NewCredential(accountName, accountKey)
	if err != nil {
		log.Fatal(err)
	}

	// Create a Pipeline, using whatever PipelineOptions you need.
	pipeline := azureblob.NewPipeline(credential, azblob.PipelineOptions{})

	// Create a *blob.Bucket.
	// The credential Option is required if you're going to use blob.SignedURL.
	ctx := context.Background()
	b, err := azureblob.OpenBucket(ctx, pipeline, accountName, containerName, &azureblob.Options{Credential: credential})
	if err != nil {
		log.Fatal(err)
	}

	// Now we can use b to read or write files to the container.
	data, err := b.ReadAll(ctx, "my-key")
	if err != nil {
		log.Fatal(err)
	}
	_ = data
}

Example (Open)

package main

import (
	"context"

	"gocloud.dev/blob"
)

func main() {
	ctx := context.Background()

	// Open creates a *blob.Bucket from a URL.
	// This URL will open the container "mycontainer" using default
	// credentials found in the environment variables
	// AZURE_STORAGE_ACCOUNT plus at least one of AZURE_STORAGE_KEY
	// and AZURE_STORAGE_SAS_TOKEN.
	b, err := blob.OpenBucket(ctx, "azblob://mycontainer")
	_, _ = b, err
}

Example (SasToken)

package main

import (
	"context"
	"log"

	"github.com/Azure/azure-storage-blob-go/azblob"
	"gocloud.dev/blob/azureblob"
)

func main() {
	const (
		// Your Azure Storage Account and SASToken.
		accountName = azureblob.AccountName("my-account")
		sasToken    = azureblob.SASToken("my-SAS-token")
		// The storage container to access.
		containerName = "mycontainer"
	)

	// Since we're using a SASToken, we can use anonymous credentials.
	credential := azblob.NewAnonymousCredential()

	// Create a Pipeline, using whatever PipelineOptions you need.
	pipeline := azureblob.NewPipeline(credential, azblob.PipelineOptions{})

	// Create a *blob.Bucket.
	// Note that we're not supplying azureblob.Options.Credential, so SignedURL
	// won't work. To use SignedURL, you need a real credential (see the other
	// example).
	ctx := context.Background()
	b, err := azureblob.OpenBucket(ctx, pipeline, accountName, containerName, &azureblob.Options{SASToken: sasToken})
	if err != nil {
		log.Fatal(err)
	}

	// Now we can use b to read or write files to the container.
	data, err := b.ReadAll(ctx, "my-key")
	if err != nil {
		log.Fatal(err)
	}
	_ = data
}

Index

• Constants
• Variables
• func NewCredential(accountName AccountName, accountKey AccountKey) (*azblob.SharedKeyCredential, error)
• func NewPipeline(credential azblob.Credential, opts azblob.PipelineOptions) pipeline.Pipeline
• func OpenBucket(ctx context.Context, pipeline pipeline.Pipeline, accountName AccountName, ...) (*blob.Bucket, error)
• type AccountKey
  • func DefaultAccountKey() (AccountKey, error)
• type AccountName
  • func DefaultAccountName() (AccountName, error)
• type Options
• type SASToken
  • func DefaultSASToken() (SASToken, error)
• type URLOpener
  • func (o *URLOpener) OpenBucketURL(ctx context.Context, u *url.URL) (*blob.Bucket, error)

Examples

• Package
• Package (Open)
• Package (SasToken)

Constants

const Scheme = "azblob"

Scheme is the URL scheme gcsblob registers its URLOpener under on blob.DefaultMux.

Variables

var DefaultIdentity = wire.NewSet(
	DefaultAccountName,
	DefaultAccountKey,
	NewCredential,
	wire.Bind(new(azblob.Credential), new(azblob.SharedKeyCredential)),
	wire.Value(azblob.PipelineOptions{}),
)

DefaultIdentity is a Wire provider set that provides an Azure storage account name, key, and SharedKeyCredential from environment variables.

var SASTokenIdentity = wire.NewSet(
	DefaultAccountName,
	DefaultSASToken,
	azblob.NewAnonymousCredential,
	wire.Value(azblob.PipelineOptions{}),
)

SASTokenIdentity is a Wire provider set that provides an Azure storage account name, SASToken, and anonymous credential from environment variables.

Functions

func NewCredential

func NewCredential(accountName AccountName, accountKey AccountKey) (*azblob.SharedKeyCredential, error)

NewCredential creates a SharedKeyCredential.

func NewPipeline

func NewPipeline(credential azblob.Credential, opts azblob.PipelineOptions) pipeline.Pipeline

NewPipeline creates a Pipeline for making HTTP requests to Azure.

func OpenBucket

func OpenBucket(ctx context.Context, pipeline pipeline.Pipeline, accountName AccountName, containerName string, opts *Options) (*blob.Bucket, error)

OpenBucket returns a *blob.Bucket backed by Azure Storage Account. See the package documentation for an example and https://godoc.org/github.com/Azure/azure-storage-blob-go/azblob for more details.

Types

type AccountKey

type AccountKey string

AccountKey is an Azure storage account key (primary or secondary).

func DefaultAccountKey

func DefaultAccountKey() (AccountKey, error)

DefaultAccountKey loads the Azure storage account key (primary or secondary) from the AZURE_STORAGE_KEY environment variable.

type AccountName

type AccountName string

AccountName is an Azure storage account name.

func DefaultAccountName

func DefaultAccountName() (AccountName, error)

DefaultAccountName loads the Azure storage account name from the AZURE_STORAGE_ACCOUNT environment variable.

type Options

type Options struct {
	// Credential represents the authorizer for SignedURL.
	// Required to use SignedURL.
	Credential *azblob.SharedKeyCredential

	// SASToken can be provided along with anonymous credentials to use
	// delegated privileges.
	// See https://docs.microsoft.com/en-us/azure/storage/common/storage-dotnet-shared-access-signature-part-1#shared-access-signature-parameters.
	SASToken SASToken
}

Options sets options for constructing a *blob.Bucket backed by Azure Block Blob.

type SASToken

type SASToken string

SASToken is an Azure shared access signature. https://docs.microsoft.com/en-us/azure/storage/common/storage-dotnet-shared-access-signature-part-1

func DefaultSASToken

func DefaultSASToken() (SASToken, error)

DefaultSASToken loads a Azure SAS token from the AZURE_STORAGE_SAS_TOKEN environment variable.

type URLOpener

type URLOpener struct {
	// AccountName must be specified.
	AccountName AccountName

	// Pipeline must be set to a non-nil value.
	Pipeline pipeline.Pipeline

	// Options specifies the options to pass to OpenBucket.
	Options Options
}

URLOpener opens Azure URLs like "azblob://mybucket".

func (*URLOpener) OpenBucketURL

func (o *URLOpener) OpenBucketURL(ctx context.Context, u *url.URL) (*blob.Bucket, error)

OpenBucketURL opens the Azure Storage Account Container with the same name as the host in the URL.